The present invention relates to data communications, and more particularly, to methods and arrangements for transmitting data for over wires connected between devices located near one another, for example, within a multiple structure campus environment or a single structure business or home environment.
In the future, it is expected that homes will have several computing devices and other data-dependent appliances that will need to be interconnected or networked together. These xe2x80x9ccomputing resourcesxe2x80x9d will be configured to exchange information with one another in the form of data that is transmitted over one or more communications resources within the home environment. To allow for such networking within the home environment, cost effective communication resources need to be developed.
Baseband Ethernet technology is currently being employed in many business environments to provide similar networking capabilities between current computing resources. For example, a baseband Ethernet technology known as 10 BASE-T Ethernet is becoming common because it provides a fairly high data rate and utilizes twisted pair wires, similar to those used for telephones, rather than coaxial cables to interconnect the computing resources.
The electrical and operational configuration of a 10 BASE-T network is specified by the Institute for Electrical and Electronic Engineers (IEEE) 802.3 standard. A 10 BASE-T network provides a 10 megabit per second (Mbps) data channel between computing resources. In accordance with the IEEE 802.3 standard, a Carrier Sense, Multiple Access with Collision Detection (CSMA/CD) protocol is employed to allow the computing resources to utilize the shared communications resource, in this case two twisted pair wires (i.e., one twisted pair for transmitting and one twisted pair for receiving).
A 10 BASE-T network employs conventional baseband transmission techniques, and as such does not require a carrier signal or additional modulation. The data in the 10 Mbps channel is, however, Manchester encoded prior to transmission through the twisted pair wire to embed timing information within the transmitted data signal. Thus, each of the computing resources typically includes a network interface circuit or card (NIC) that provides the necessary Manchester encoding and decoding capability.
As a result of the Manchester encoding, however, the actual data transmission rate associated with the 10 Mbps channel is essentially doubled to 20 Mbps. Therefore, it is necessary that the communication media or resource (e.g., twisted pair wire) be capable of providing at least 20 Mbps bandwidth to effectively carry the Manchester encoded data. The traditional twisted pair wiring that is installed in most homes for use with the telephone is not shielded and/or designed to carry 20 Mbps of digital data, and as such typically cannot provide this needed bandwidth. Thus, bringing 10 BASE-T networking to a home environment usually requires an investment in new, higher-bandwidth rated, twisted pair wiring (e.g., shielded). For many homeowners this cost will be prohibitive. Additionally, many homes have only one twisted pair wire installed, rather than the required two twisted pair wires.
Some other proposed solutions for home networking include standard modem technology and digital subscriber line (XDSL) technology. These technologies are directed towards providing external connectivity through existing telephone and related data communication services, as well as potentially providing limited internal home networking. One of the problems associated with standard modem technology, however, is that it is currently limited to data speeds of about 56 kbps and often requires very complicated circuitry. Although, xDSL technology can transmit data at a much higher rate than standard modem technology, for example, up to about 4 Mbps, the cost of implementing such is very high and typically requires very complicated modulation methods.
There are technologies and products that are directed more towards home networking. For example, Tut Systems Inc., of Pleasant Hill, Calif., produces a HR1300T communication device. The HR1300T uses a xe2x80x9ctime modulation line codexe2x80x9d to provide an in-home network over existing phone lines. However, this modulation scheme currently only provides about a 1 to 2 Mbps data rate.
Therefore, as can be appreciated, there is a need to provide improved methods and arrangements that allow standard home wiring, or other inexpensive or existing communication media, to be used as a communication resource between computing resources. Preferably, the methods and arrangements not only provide the necessary bandwidth, but are also cost effective, essentially transparent to the user/computing resource, and simple to implement.
In accordance with certain aspects of the present invention, methods and arrangements are provided that allow computing resources that are located near to one another, for example, in a home environment or closely spaced multiple structure campus environment, to communicate over existing wires using radio frequency (RF) signals. In accordance with other aspects of the present invention, the methods and arrangements provide a cost effective networking capability that is, essentially transparent to the user/computing resource, and simple to implement within existing structures, for example, over wires that are about 1000 feet long.
By way of example, in accordance with certain aspects of the present invention, a standard Ethernet data signal, from a first device, is modulated using conventional RF modulation techniques and then transmitted for limited distances over existing telephone wiring to one or more other devices, which then demodulate the RF signal and recover the original Ethernet data signal. Thus, in this exemplary embodiment, the operating protocol of the Ethernet network (i.e., the CSMA/CD protocol) is allowed to operate seamlessly without knowledge of the additional communication processes.
In accordance with one embodiment of the present invention, an arrangement for transmitting digital data output by a first device to a second device over a twisted pair wire is provided. The arrangement includes a modulator and a line driver. The modulator is configured to receive a data signal that is output by the first device. The modulator modulates the data signal, using at least one radio frequency (RF) carrier, to produce a corresponding modulated data signal. For example, in certain embodiments the RF carrier has a frequency or center frequency of between about 1 MHz and about 280 MHz.
The modulated data signal is then provided to the line driver, which is configured to output the modulated data signal through at least one twisted pair wire to the second device, based on a carrier sense multiple access (CSMA) protocol.
In accordance with certain other embodiments of the present invention the modulator employs either a quadrature phase shift keying (QPSK), binary phase shift keying (BPSK), quadrature amplification modulation (QAM), or like technique. For example, in certain embodiments, the modulator employs differential QPSK techniques and the RF carrier preferably has a frequency between about 10 MHz and about 70 MHz. In other embodiments, the modulator employs differential BPSK techniques and the RF carrier preferably has a frequency between about 70 MHz and about 200 MHz. In still other embodiments, the modulator employs QAM techniques and the RF carrier preferably has a frequency between about 1 MHz and about 10 MHz.
In accordance with further embodiments of the present invention, the arrangement also includes a detector that is configured to receive the modulated data signal from the twisted pair wire and output a substantially reproduced modulated data signal to a demodulator that is configured to demodulate and otherwise substantially reproduce the data signal therefrom.
The above stated needs and others are also met by a method for transmitting data over twisted pair wire within a home environment, in accordance with certain embodiments of the present invention. The method includes outputting a digital signal from a first device, modulating the digital signal to produce a corresponding radio frequency (RF) signal, and transmitting the RF signal through at least one twisted pair wire to the second device using a carrier sense multiple access (CSMA) protocol.
In accordance with still another embodiment of the present invention, a method is provided for transferring data between a plurality of devices in a home environment, wherein the plurality of devices are interconnected by twisted pair wire that is also configured for telephone access. The method includes determining if the twisted pair wire is currently being used for transferring data by any of the plurality of devices, and provided that the twisted pair wire is not currently being used, then outputting a digital data stream from one of the plurality of devices, using the digital data stream to produce a corresponding RF signal using either QPSK, BPSK, QAM, or like techniques, and providing the RF signal through the twisted pair wire to at least one of the plurality of devices.